The present invention relates to a method and apparatus for controlling a motor vehicle, and in particular for efficiently controlling an engine power train comprising an engine and a transmission, in accordance with information such as a travelling condition, to realize an acceleration or deceleration requested by a driver.
Japanese Patent Laid-Open No. 345541/1992 discloses a method which controls at least one of the engine torque adjustment means, transmission gear ratio adjustment means, and braking force adjustment means, so that a target acceleration/deceleration requested by a driver equals the actual motor vehicle acceleration/deceleration.
In a system for performing control in accordance with only a target acceleration/deceleration requested by a driver, such as in the above prior art, a traffic accident or speeding may occur if the driver erroneously recognizes a forward traveling condition, or responds too slowly to a traveling condition. Moreover, previous confirmation of a road gradient or a corner becomes insufficient, and it is difficult to secure a sufficient driving force before entering a slope or corner by controlling a transmission gear ratio.
It is an object of the present invention to provide a control method and apparatus capable of controlling an engine power train so that actual vehicle acceleration/deceleration equals a target acceleration/deceleration requested by a driver, under a normal safe traveling condition. It is another object of the invention to secure both operability and safety, giving preference, however, to safety by changing the target acceleration/deceleration if the driver encounters a dangerous traveling condition.
These and other objects and advantages are achieved by the control arrangement according to the invention, which comprises detectors for detecting acceleration/deceleration requested by a driver, as well as actual motor vehicle speed; a unit for setting a target acceleration/deceleration in accordance with the requested acceleration/deceleration detection and the motor vehicle speed; a unit for detecting a traveling road conditions, including an obstacle such as a forward motor vehicle; a dangerous traveling decision unit for deciding whether a traveling condition is dangerous, based on detected road conditions; and a unit for changing the set target value when dangerous traveling is determined to exist.
The acceleration/deceleration detector unit detects an accelerator by detecting a positive accelerator pedal depression by a driver, and detects deceleration by detecting a negative acceleration depression by the driver, so as to release the accelerator, and a brake pedal depression force. The vehicle speed detection unit uses a signal output from a rotation sensor on an output shaft or a wheel rotation shaft of a transmission to convert the signal value into a motor vehicle speed. The target acceleration/deceleration unit sets a motor-vehicle is acceleration/deceleration requested by a driver in accordance with the results detected by the acceleration/deceleration detector unit and the motor vehicle speed detector unit. The road condition detection unit detects approaching motor vehicles and other obstacles, and a road-surface friction coefficient by means of a camera, radar, navigation map information, and other vehicle infrastructure equipment (hereinafter, xe2x80x9cinfra-equipmentxe2x80x9d) directed to the road ahead. The dangerous traveling decision unit decides whether the present motor vehicle traveling falls into a dangerous traveling condition several seconds later (this value changes with the motor vehicle speed) in accordance with the results detected by the road condition detection unit and the motor vehicle speed detector unit. The target value change unit changes the set target acceleration/deceleration in response to a determination of dangerous travel by the dangerous traveling decision unit.
A target braking/driving torque operation unit transmits a target braking/driving torque to a wheel in accordance with the results obtained from road condition detection unit, target acceleration/deceleration unit, motor vehicle speed detector unit, and target value change unit. Moreover, in accordance with this result, a control input of the following control unit is operated. Control input operation means operates a final control input by using a motor vehicle speed, a sufficient driving torque corresponding to the motor vehicle speed, road gradient, target acceleration/deceleration, and target braking/driving torque and considering fuel consumption, and operability and safety intended by a driver. Controls such as engine torque control, the transmission gear ratio control, and braking force control adjust each power train control in accordance with the above determined and detected results.
As described above, the present invention makes it possible to secure both operability and safety because an actual acceleration/deceleration is controlled equal a requested acceleration/deceleration at the time of safe traveling; while safety priority control is executed during a dangerous traveling condition.
Other objects, advantages and novel features of the present invention will become apparent from the following detailed description of the invention when considered in conjunction with the accompanying drawings.